This invention relates to a process for dyeing yarn hanks. More particularly, according to this invention, it is possible to dye yarn hanks without causing any loss of the properties possessed by the yarn itself and without effecting the elastic properties of each yarn.
In the prior art it is known to use a dipping system for dyeing yarn hanks, but it is well known that such a system will consume a great amount of dyestuffs, chemicals and vapor because such system requires the use of a high ratio of dye applied to dye used, i.e. a ratio of approximately 1:40 or 50. Accordingly, this prior art system is very expensive to use. Furthermore, such prior art has the defects that the hanging portion of the yarn hanks supported on spindles in the bath may not be dyed or may be formed as an uneven portion because the yarn hanks are suspended from the spindles continuously during the dyeing operation, that there occurs loss of yarn during the unraveling operation of the treated yarn, or that there may appear dye spots on the yarns during the dipping operation so that the coloration of the yarns is not uniform.
On the other hand, there are also known in the prior art spray systems for dyeing yarn hanks. Also, the disadvantages of the above-mentioned dipping system have been somewhat improved by rotating the spindles together with the yarn hanks and by elongating the yarns shrunk during the dyeing operation of the dipping system. Still, however, the operation of unraveling the yarn hanks in such dipping system remains inefficient. Further, even though the spray system requires the use of less dye than the dipping system, it is still difficult to obtain good elongation and formation of the yarns.